Immunohistochemical examination of rat
skeletal muscle during graft-versus-host disease
(GVHD), a systemic immune reaction, was performed to
investigate specific immune reactivities focusing on
major histocompatibility complex (MHC) expression
and inflammatory cell infiltration of skeletal muscle
during a systemic immune reaction. MHC class 11
expression and inflammatory cell infiltration did not
increase. MHC class 1 was expressed along the contour
of muscle fibres, and most strongly expressed by the
cells which were distributed throughout the endomysium
and perimysium. Seventy-six percent of these MHC
class I+ cells carried endothelial cell-markers, while 24%
of them did not. The latter cells were revealed not to be
inflammatory cells such as lymphocytes, granulocytes or
macrophages when examined by immunostaining using
severa1 exudate-cell markers. Neither were they
myosatellite cells because they were located outside the
basement membrane. These results may be useful for
considering animal models of inflammatory myopathies
such as polymyositis and dermatomyositis.